The modern sport of fencing is hundreds of years old. Historically, referees and bout directors awarded points (or touches—where one opponent's weapon blade or tip makes contact with the target area of the other opponent) by visually observing two opponents and determining whether a touch occurred and whether the fencer scoring the touch should be awarded a point based on existing rules. The object of saber fencing, based on cavalry fencing on horseback, is to score touches by contacting a blade or tip of a fencer's weapon with an opponent's target area (above that opponent's waist including his arms and head). The object of foil fencing is to score touches by contacting the tip of a fencer's weapon with an opponent's target area (the opponent's torso). The object of epee fencing, based on first-blood duels, is to score touches by contacting the tip of a fencer's weapon with an opponent's target area (any part of the opponent's body). Each form of modern sport of fencing is very rapid. Often actions, contacts, and target areas are difficult to visually see. Modern fencing weapons are so light that skilled fencers can manipulate them with extreme speed in flurries of action. This speed renders it difficult to determine when touches are scored. Even where several officials are employed to judge a match, visual identification of scoring maneuvers is difficult. Disagreement between officials often occurs, due to the inconsistency in the quality of perspective enjoyed by the various officials. Moreover, judgment by visual observation is a subjective criterion, and the acuity of vision may vary among officials, and even in the same official.
In the 1970s electronic circuits were used to aid in awarding touches. FIG. 1 depicts the current state of the art fencing scoring system. Each fencer X, Y holds a weapon 12, 14 which includes a blade 20 connected to a wire running down each fencer's sleeve (not shown) and connected behind each fencer to a reel wire 24, 26 affixed to a retractable reel 28, 30. Each fencer X, Y wears a jacket 21, 22 which can be made of a conductive material, a mask 30 which can be made of conductive material, and a wire 31 connecting the mask to the jacket 21. The terminal of the reel wire 24, 26 is also connected electrically to the fencer's jacket 21, 22. Each reel 28, 30 is connected to an electrical scoring apparatus 10 that has indicators Wx, Cx, Wy, Cy which alternately illuminate to indicate a touch. If the weapon being fenced is saber, then when fencer Y in FIG. 1 contacts fencer X with any portion of the blade 20 of weapon 14 on a conductive area of either jacket 22 or mask 33, a circuit connects and indicator light Wy indicates fencer A scored a touch. A referee or director D will use this information and his or her visualization of the action to decide whether fender Y's touch should be awarded a point. When fencer X in FIG. 1 contacts fencer Y with the blade 16 of saber 12 on fencer Y's conductive area of either jacket 22 or mask 33, a circuit connects and indicator light Wx illuminates. Often both lights Wy and Wx will illuminate and a director or referee will need to determine to which fencer, if any, a touch should be awarded according to the rules of saber fencing.
Foil fencing includes a similar configuration to the saber configuration of FIG. 1, except each fencer X, Y hold a foil and jackets 21, 22 have a conductive target area comprising the fencer's torso. A valid touch signal in foil includes the breaking of a first circuit and completing a second. A foil has a movable contact on its tip, which is depressed whenever the tip touches an object, breaking the first electrical circuit. Each contestant wears a vest-like garment which covers the valid target portion of his body. The vest has a conductive surface, and is connected in a second circuit between the electrical scoring apparatus 10 and the opponent's foil. The movable contact on each foil is itself conductive. When the movable contact of one fencer's foil touches the opponent's conductive vest, the second electrical circuit is completed, and the first circuit is broken, producing a valid touch signal (thus illuminating respective indicator Wx or Wy). An invalid touch in foil is indicated merely by the breaking of the first circuit (thus illuminating respective indicator Cx, Cy), since in an invalid touch, the foil fails to contact the opponent's vest.
Epee fencing includes a similar configuration to the saber configuration of FIG. 1, except each fencer X, Y hold an epee and wear a jacket 21, 22 that need not include a conductive area. A touch signal in epee constitutes simply the making of one circuit. The movable contact in the epee touch sensor assembly completes the circuit on depression in the course of a touch. Errant touches on the piste 35 or on the opponent's weapon body are not scored. Accordingly, if a fencer's epee tip touches the piste 35, or his opponent's weapon, the electrical scoring apparatus 10 disables the scoring indicators, preventing the registration of a touch in response to such errant touches. The movable contact on the epee tip is conductive as in the case of the foil. It is connected to a portion of the electrical scoring apparatus 10 which, if grounded, prevents actuation of the valid touch indicators. The piste 35 is grounded, as is the body of each weapon 12, 14, so that errant touches on the weapon body or the piste 35 are not counted as scores.
A problem associated with the state of the art fencing system is that it requires jackets, vests and masks made of conductive fabrics and materials which do not wear well with sweat or frequent washing. They are constricting to wear and inhibit a fencer's maneuverability and motion. Often fencers have to wear multiple jackets for safety reasons and the conductive garments are an additional layer which can be uncomfortable and hot for fencers who are exerting themselves. Further, fencers are required to be connected to wires such as the cords in their sleeves, reel wires 24, 26, and mask wire 31 which frequently break and easily become tangled and uncomfortable. Additionally, if the equipment fails to connect a circuit in the proper way due to oxidation of a weapon blade or tip or a conductive garment, target area connectivity dead spots, an overabundance of sweat, a malfunction of wire, or the electrical connection anywhere between electrical scoring apparatus 10 weapon 12, 14 all can affect the outcome of a match and cause for difficulty in scoring a bout. The circuitry used in current state of the art fencing scoring systems is somewhat unreliable and scoring equipment is prone to malfunction, leading to inaccurate scoring results and lengthy downtime while the fencer attempts to “fix” any malfunctioning fencing equipment. Additionally, fencing equipment can be quite costly as simply to engage in electrical scoring a pair of fencers requires electrical scoring apparatus 10, two reels 28, 30, two electrical wires connecting reels 28, 30 to electrical scoring apparatus 10, wires in fencers' sleeves, etc which can cost thousands of dollars.
Contact sensing probes are used in industry to detect capacitance of non-conductive materials such as textiles. Capacitive sensors measure capacitance by contact and non-contact techniques. Non-contact sensors measure disruption in capacitive electron flow. Contact capacitive sensors detect capacitance changes when a lead contacts a surface. Contact capacitive sensors can detect different material properties of the surface they contact. For example, contacting a metal material versus a non-conductive material, or contacting concrete versus plaster. Capacitive sensors can also distinguish between various kinds of textiles based on their relatively unique resistivity.
Capacitance describes how the space between two conductors affects an electric field between them. If two metal plates are placed with a gap between them and a voltage is applied to one of the plates, an electric field will exist between the plates. This electric field is the result of the difference between electric charges that are stored on the surfaces of the plates. Capacitance refers to the “capacity” of the two plates to hold this charge. In single probe sensing, a conductive probe contacts a surface. A sensor measures changes in current across a resistor connected to the probe to determine the dielectric constant of the contacted surface. The sensing surface of the probe is the electrified plate and what you're measuring is the target. Capacitive sensors can be very effective in measuring presence, density, thickness, and location of non-conductors as well. Non-conductive materials like plastic have a different dielectric constant than air. The dielectric constant determines how a non-conductive material affects capacitance between two conductors. When a non-conductor is inserted between the probe and a stationary reference target, such as the human body, the sensing field passes through the material to the grounded target. The presence of the non-conductive material changes the dielectric and therefore changes the capacitance. The capacitance will change in relationship to the thickness and density of the material.
The invention overcomes the problems of the prior art by providing a contact sensing device and system which embodies all the required sensing components in a handheld device and does not require conductive contact surfaces to detect contact with a target area. The invention is also entirely self-contained and requires no additional wiring to be connected outside the personal system. In the fencing system example, this will remarkably increase the system reliability, the fencer's comfort and maneuverability, and reduce the cost and quantify of equipment subject to malfunction and repair needed in the prior art system.
The invention achieves this in a first aspect by a handheld device for sensing contact with a substance which includes a capacitive sensor that includes an elongate portion configured to generate at least one sense signal upon said elongate portion contacting at least one substance; a processor for receiving the sense signal from the capacitive sensor, processing the at least one sense signal to determine a property of the at least one substance, and for generating an indicator signal; and an indicator which receives the indicator signal and indicates if the capacitive sensor contacts the substance.
In one embodiment a portion of the elongate portion of the capacitive sensor includes a contact sensing lead for sensing contact between a lateral side of a portion of the elongate portion and the at least one substance.
In another embodiment, the elongate portion is a blade or tip of a fencing weapon.
In another embodiment the device includes a plurality of indicators and the processor determines which indicator or indicators receives an indicator signal based on the determined property of the at least one substance. The processor can contain logic for determining which of the plurality of indicators receives an indicator signal.
In one embodiment, the property of the at least one substance is a material characteristic. In another embodiment, the property of the at least one substance is conductivity. In another embodiment the property of the at least one substance represents contact on a target area. The processor can also send an indicator signal to one of the plurality of indicators if the capacitive sensor contacts the target area and the processor sends an indicator signal another of the plurality of indicators if the capacitive sensor contacts an area other than the target area.
In another embodiment, the property of the at least one substance is the presence of another device. The processor can be configured to send an indicator signal to one of the plurality of indicators if the capacitive sensor detects the presence of another device.
In another embodiment, the device includes at least one motion sensor for sensing motion of the device. The motion sensor can sense acceleration, speed, and/or direction. The motion sensor can send a motion signal to the processor and the processor processes the motion signal to generate a motion indicator signal.
In one embodiment, the device includes a counter for outputting a count of indicator signals and a memory for storing said count. In still another embodiment, the device includes a display for displaying the count.
In one embodiment, the device includes a power source. In another embodiment the device includes a wireless communication device for transmitting at least one of the indicator signal and the motion indicator signal. The wireless communication device can also receive at least one indicator signal from at least one other device.
In one aspect the invention includes a system for scoring contact between a device and at least one substance including: at least one device for sensing contact with a substance that includes a device for sensing contact with a substance which includes a capacitive sensor that includes an elongate portion configured to generate at least one sense signal upon said elongate portion contacting at least one substance; a processor for receiving the sense signal from the capacitive sensor, processing the at least one sense signal to determine a property of the at least one substance, and for generating an indicator signal; and an indicator which receives the indicator signal and indicates if the capacitive sensor contacts the substance and at least one target comprising at least one substance detectible by the device.
In one embodiment the system includes at least two devices for sensing contact. In another embodiment the two devices communicate wirelessly.
Other aspects and advantages of embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.